Martin Carpen is Minnakht's main and for a long time only character.
Martin Carpen is a short man, standing only 5'6", and that's when not hunched, what is his usual stance and detracts further 2-3 inches from his height. He wears a large amount of clothing, including an undershirt, a shirt, thick pants with suspenders, then a further jacket and multiple aprons. His boots are also large and plated with metal, and he wears an orange hardhat all the time, which covers the fact he's nearly bald despite his age of 34.
An important feature of Martin's appearance are his goggles, also worn all the time. Martin's eyes are highly sensitive, what causes him to go blind in bright light. The goggles prevent that, letting him see in bright places and protecting his eyes from sudden flashes as well.
Martin has been a Worldgineer for a long time, as evidenced by his rank. He also spent an amount of time in the military of a nondescript faction, from where his story in FAW I starts. He was said to be a weapon-maker, driven to fight himself when all the other soldiers fell in the battlefield.
As mentioned, Martin is an adept weapon-maker and metalworker, owning a metal shop in Waterford, Ireland. He is also skilled with operating all sorts of Hammerspace Technology, and can even modify it. He is also a good shot with a shotgun, especially his own, custom one, using an ammo tape. He also owns A Spear, a curiously named weapon consisting of a leaf-shaped blade on a long shaft, with the other side of the shaft ending with a leathery sack containing lead shot, used for blunt, stunning strikes. A Spear can produce a blade akin to a lightsaber above the whole length of its shaft and along the blade's edge, which quality has been often used for various armour-piercing attacks.
By the end of FAW VII, impressed by Rayleigh's and others' prowess on the battlefield, Martin took a several-week course in "the six arts" and "willpower", a set of abilities available for normal humans through intensive training, which allow for exceeding human capabilities. (and ripped off directly from One Piece, which the author was smoking at the time.)